1. Field of the Invention
The invention relates to a method for detecting an incorrect position of a semiconductor wafer during a high-temperature treatment of the semiconductor wafer in a quartz chamber which is heated by IR radiators. The semiconductor wafer is lying on a rotating support and is held at a specific temperature with the aid of a control system. The invention also relates to a device for carrying out the method.
2. The Prior Art
A semiconductor wafer is subjected to a high-temperature treatment in a quartz chamber, when it is intended to condition the semiconductor wafer. Examples of conditioning include annealing, rapid thermal annealing and rapid thermal processing (RTP). Other high-temperature treatment includes doping the wafer or depositing a layer of material on one or both sides of the semiconductor wafer (chemical vapor deposition (CVD), atmospheric pressure CVD (ACVD), reduced pressure CVD (RCVD), epitaxy). For this purpose, the semiconductor wafer has to lie on a support. The support is rotated during the treatment to ensure that the semiconductor wafer is treated as uniformly as possible.
One decisive factor in the success of the high-temperature treatment is that the semiconductor wafer lies in the planned position on the support and maintains this position throughout the treatment. Even a slightly incorrect position of the semiconductor wafer in which the semiconductor wafer does not lie parallel to the support may have undesirable consequences. For example, if the semiconductor wafer, during a coating treatment, does not lie parallel to the support, but rather is tilted slightly out of the parallel position on the support, the thickness of the layer deposited may not be uniform. Crystal defects within the semiconductor wafer may occur.
Often, the support for the semiconductor wafer is raised in the edge region. The intention is to avoid incorrect positions and to allow the semiconductor wafer to be centered. Despite such precautionary measures, it is still possible that the semiconductor wafer may lie in an undesired position on the support. Semiconductor wafers which are faulty for this reason have to be identified and separated out following the treatment. This procedure is complex and uneconomical.